And the negative effects happened irrespective of diet, health concerns or socio-demographic factors.

The findings showed no clear link between sleep duration and body weight in those with a low genetic risk of obesity.

Study author Dr Jason Gill said: 'These data show that in people with high genetic risk for obesity, sleeping for too short or too long a time, napping during the day and shift work appears to have a fairly substantial adverse influence on body weight.

'However, the influence of adverse sleep characteristics on body weight is much smaller in those with low genetic obesity risk - these people appear to be able to 'get away' with poorer sleep habits to some extent.'

Co-author Dr Carlos Celis added: 'It appears that people with high genetic risk for obesity need to take more care about lifestyle factors to maintain a healthy body weight.

'Our data suggest that sleep is another factor which needs to be considered, alongside diet and physical activity.'